The present invention relates to data processing used for a full-color printing related equipment such as a printer, a video printer, a scanner or the like, an image processor for forming computer graphic images or a display device such as a monitor. More specifically, the invention relates to a color conversion device and a color conversion method for performing color conversion for image data of three colors of red, green and blue in accordance with an equipment used.
Color conversion in printing is an indispensable technology for compensating for deterioration of image quality such as that due to color mixing properties caused by factors such as that the ink is not of a pure color, or non-linearity (in the hue) of he image-printing, and to output a printed image with a high color reproducibility. Also, in a display device such as a monitor or the like, color conversion is performed in order to output (display) an image having desired color reproducibility in accordance with conditions the device is used or the like when an inputted color signal is to be displayed.
Conventionally, two methods have been available for the foregoing color conversion: a table conversion method and a matrix calculation method.
The table conversion method is a method for inputting image data of red, green and blue (referred to xe2x80x9cR, G and Bxe2x80x9d, hereinafter) and obtaining image data of R, G and B stored beforehand in a memory such as ROM or complementary color data of yellow, magenta and cyan (referred to as xe2x80x9cY, M and Cxe2x80x9d, hereinafter). Since an arbitrary conversion characteristic can be employed, this table conversion method has an advantageous capability of executing color conversion with good color reproducibility.
However, in a simple structure for storing data for each combination of image data, a large-capacity memory of about 400 Mbit must be used. For example, even in the case of a compression method for memory capacity disclosed in Japanese Patent Kokai Publication No. S63-227181, memory capacity is about 5 Mbit. Therefore, a problem inherent in the table conversion system is that since a large-capacity memory is necessary for each conversion characteristic, it is difficult to implement the method by means of an LSI, and it is also impossible to deal with changes in the condition under which the conversion is carried out.
On the other hand, in the case of the matrix calculation method, for example, for obtaining printing data of Y, M and C from image data of R, C and B, the following formula (27) is used as a basic calculation formula.                               [                                                    Y                                                                    M                                                                    C                                              ]                =                              (            Aij            )                    ⁡                      [                                                            R                                                                              G                                                                              B                                                      ]                                              (        27        )            
Here, i=1 to 3, and j=1 to 3.
However, by the simple linear calculation of the formula (27), it is impossible to provide a good conversion characteristic because of a non-linearity of an image-printing or the like.
A method has been proposed for providing a conversion characteristic to improve the foregoing characteristic. This method is disclosed in Japanese Patent Application Kokoku Publication H2-30226, directed to xe2x80x9ccolor correction calculation device, and employs a matrix calculation formula (28) below.                               [                                                    Y                                                                    M                                                                    C                                              ]                =                              (            Dij            )                    ⁡                      [                                                                                                    ⁢                    R                                                                                                                                        ⁢                    G                                                                                                                                        ⁢                    B                                                                                                                                        ⁢                                          R                      *                      G                                                                                                                                                            ⁢                                          G                      *                      B                                                                                                                                                            ⁢                                          B                      *                      R                                                                                                                                                            ⁢                                          R                      *                      R                                                                                                                                                            ⁢                                          G                      *                      G                                                                                                                                                            ⁢                                          B                      *                      B                                                                                                                                                            ⁢                    N                                                                        ]                                              (        28        )            
Here, N is a constant, i=1 to 3, and j=1 to 10.
In the foregoing formula (28), since image data having a mixture of an achromatic component and a color component is directly used, mutual interference occurs in computation. In other words, if one of the coefficients is changed, influence is given to the components or hues other than the target component or hue (the component or hue for which the coefficient is changed). Consequently, a good conversion characteristic cannot be realized.
A color conversion method disclosed in Japanese Patent Application Kokai Publication H7-170404 is a proposed solution to this problem. FIG. 29 is a block circuit diagram showing the color conversion method for conversion of image da of R, G and B into printing data of C, M and Y, disclosed in Japanese Patent Application Kokai Publication H7-170404. A reference numeral 100 denotes a complement calculator; 101, an minimum and maximum calculator; 102, a hue data calculator; 103, a polynomial arithmetic unit; 104, a matrix calculator; 105, a coefficient generator; and 106, a synthesizer.
Next, the operation will be described. The complement calculator 100 receives image data R, G and B, and outputs complementary color data Ci, Mi and Yi which have been obtained by determining 1""s complements. The minimum and maximum calculator 101 outputs a maximum value xcex2 and a minimum value xcex1 of this complementary color data and an identification code S for indicating, among the six hue data, data which are zero.
The hue data calculator 102 receives the complementary color data Ci, Mi and Yi and the maximum and minimum values xcex2 and xcex1, and outputs six hue data r, g, b, y, m and c which are obtained by executing the following subtraction: r=xcex2xe2x88x92Ci, g=xcex2xe2x88x92Mi, b=xcex2xe2x88x92Yi, y=Yixe2x88x92xcex1, m=Mixe2x88x92xcex1, and c=Cixe2x88x92xcex1. Here, among the six hue data, at least two assume the value zero.
The polynomial arithmetic unit 103 receives the hue data and the identification code, selects, from r, g and b, two data Q1 and Q2 which are not zero and, from y, m and c, two data P1 and P2 which are not zero. Based on these data, the polynomial arithmetic unit 103 computes polynomial data: T1=P1*P2, T3=Q1*Q2, T2=T1/(P1+P2), and T4=T3/(Q1+Q2), and then outputs the results of the calculation.
The coefficient generator 105 generates calculation coefficients U(Fij) and fixed coefficients U(Fij) for the polynomial data based on information regarding the identification code S. The matrix calculator 104 receives the hue data y, m and c, the polynomial data T1 to T4 and the coefficients U, and outputs a result of the following formula (29) as color ink data C1, M1 and Y1.                               [                                                    C1                                                                    M1                                                                    Y1                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    c                                                                                        m                                                                                        y                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                                                ⁢                                              c                        *                        m                                                                                                                                                                              ⁢                                              m                        *                        y                                                                                                                                                                              ⁢                                              y                        *                        c                                                                                                                                                                              ⁢                                              r                        *                        g                                                                                                                                                                              ⁢                                              g                        *                        b                                                                                                                                                                              ⁢                                              b                        *                        r                                                                                                                                                                              ⁢                                              c                        *                                                  m                          /                                                      (                                                          c                              +                              m                                                        )                                                                                                                                                                                                                                ⁢                                              m                        *                                                  y                          /                                                      (                                                          m                              +                              y                                                        )                                                                                                                                                                                                                                ⁢                                              y                        *                                                  c                          /                                                      (                                                          y                              +                              c                                                        )                                                                                                                                                                                                                                ⁢                                              r                        *                                                  g                          /                                                      (                                                          r                              +                              g                                                        )                                                                                                                                                                                                                                ⁢                                              g                        *                                                  b                          /                                                      (                                                          g                              +                              b                                                        )                                                                                                                                                                                                                                ⁢                                              b                        *                                                  r                          /                                                      (                                                          b                              +                              r                                                        )                                                                                                                                                          ]                                                          (        29        )            
The synthesizer 106 adds together the color ink data C1, M1 and Y1 and data xcex1 which is the achromatic data, and outputs printing data C, M and Y. Accordingly, the following formula (30) is used for obtaining printing data.                               [                                                    C                                                                    M                                                                    Y                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    c                                                                                        m                                                                                        y                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                                                ⁢                                              c                        *                        m                                                                                                                                                                              ⁢                                              m                        *                        y                                                                                                                                                                              ⁢                                              y                        *                        c                                                                                                                                                                              ⁢                                              r                        *                        g                                                                                                                                                                              ⁢                                              g                        *                        b                                                                                                                                                                              ⁢                                              b                        *                        r                                                                                                                                                                              ⁢                                              c                        *                                                  m                          /                                                      (                                                          c                              +                              m                                                        )                                                                                                                                                                                                                                ⁢                                              m                        *                                                  y                          /                                                      (                                                          m                              +                              y                                                        )                                                                                                                                                                                                                                ⁢                                              y                        *                                                  c                          /                                                      (                                                          y                              +                              c                                                        )                                                                                                                                                                                                                                ⁢                                              r                        *                                                  g                          /                                                      (                                                          r                              +                              g                                                        )                                                                                                                                                                                                                                ⁢                                              g                        *                                                  b                          /                                                      (                                                          g                              +                              b                                                        )                                                                                                                                                                                                                                ⁢                                              b                        *                                                  r                          /                                                      (                                                          b                              +                              r                                                        )                                                                                                                                                          ]                                +                      [                                                            α                                                                              α                                                                              α                                                      ]                                              (        30        )            
The formula (30) shows a general formula for a group of pixels.
FIG. 30A to FIG. 30F, which are schematic diagrams, show relations between six hues of red (R), green (G), blue (B), yellow (Y), cyan (C) and magenta (M) and hue data y, m, c, r, g and b, and each hue data relates to three hues.
FIG. 31A to FIG. 31F, which are schematic diagrams, show relations between the six hues and product terms y*m, r*g, c*y, g*b, m*c and b*r, and it is seen that each hue data relates to specified hue among the six hues.
Thus, each of the six product terms y*m, m*c, c*y, r*g, g*b and b*r relates to only specific hue among the six hues of red, blue, green, yellow, cyan and magenta. In other words, only y*m is an effective product term for red; m*c for blue; c*y for green; r*g for yellow; g*b for cyan; and b*r for magenta.
Also, each of the six fraction terms y*m/(y+m), m*c/(m+c), c*y/(c+y), r*g/(r+g), g*b/(g+b) and b*r/(b+r) in the formula (30) relates to only a specific hue among the six hues.
As apparent from the foregoing, according to the color conversion method shown in FIG. 29, by changing coefficients for the product terms and the fraction terms regarding the specific hue, only the target hue can be adjusted without influencing to other hues.
Each of the foregoing product terms is determined by a second-order computation for chroma, and each of the fraction terms is determined by a first-order computation for chroma. Thus, by using both of the product terms and the fraction terms, the non-linearity of an image-printing for chroma can be corrected.
However, even in this color conversion method, the problems of the non-linearity of image-printing for hues remains to be solved. Depending on the user""s preference, if an area in a color space occupied by specific hues is to be expanded or reduced, e.g., specifically, if expansion or reduction of an area of red in a color space including magenta, red and yellow is desired, the conventional color conversion method of the matrix computation type could not meet with such a desire.
The problems of the conventional color conversion method or color conversion device are summarized as follows. Where the color conversion device is of a table conversion method employing a memory such as ROM, a large-capacity memory is required, and a conversion characteristic cannot be flexibly changed. Where the color conversion device is of using a matrix calculation method, although it is possible to change only a target hue, it is not possible to correct the inter-hue areas between adjacent ones of the six hues of red, blue, green, yellow, cyan and magenta, good conversion characteristics cannot be realized throughout the entire color space.
The present invention was made to solve the foregoing problems. An object of the present invention is to provide a color conversion device and a color conversion method for performing color-conversion for each pixel of image data R, G and B, wherein independent correction is performed not only for six hues of red, blue, green, yellow, cyan and magenta but also six inter-hue areas of red-yellow, yellow-green, green-cyan, cyan-blue, blue-magenta and magenta-red. The invention further provides a conversion characteristic that can be flexibly changed, and a device where no large-capacity memories are necessary.
According to the invention, there is provided a color conversion device for performing pixel-by-pixel color conversion of image data R, G and B of three colors, red, green and blue, comprising:
calculating means for calculating a maximum value xcex2 and a minimum value xcex1 of said image data for each pixel;
hue data calculating means for calculating hue data r, g, b, y, in and c based on said image data and said maximum and minimum values xcex2 and xcex1 outputted from said calculating means h;
means for generating comparison-result data based on each hue data outputted from said hue data calculating means;
arithmetic means for performing calculation using each hue data outputted from said hue data calculating means;
coefficient generating means for generating specified matrix coefficients; and
a matrix calculator for performing matrix calculation based on the coefficients from said coefficient generating means, using the comparison-result data from said comparison-result data generating means, the output from said arithmetic means, the hue data from said hue data calculating means and said minimum value xcex1 from said calculating means, thereby to obtain color-converted image data.
With the above arrangement, it is possible to independently correct, in addition to the six hues of red, blue, green, yellow, cyan and magenta, the six inter-hue areas of red-yellow, yellow-green, green-cyan, cyan-blue, blue-magenta, and magenta-red.
It is also possible to flexibly change the conversion characteristics, and the large-capacity memory is not required.
It may be so arranged that said calculating means for calculating said maximum and minimum values xcex2 and xcex1 calculates a maximum value xcex2 and a minimum value xcex1 of the image data R, G and B,
said hue data calculating means calculates hue data r, g, b, y, m and c by subtraction in accordance with:
r=Rxe2x88x92xcex1,
g=Gxe2x88x92xcex1,
b=Bxe2x88x92xcex1,
y=xcex2xe2x88x92B,
m=xcex2xe2x88x92G,
and
c=xcex2xe2x88x92R;
based on inputted image data R, C and B and said maximum and minimum values xcex2 and xcex1 outputted from said calculating means,
said comparison-result data generating means including multiplying means for multiplying respective due data by calculation coefficients aq1 to aq6 and ap1 to ap6; means for obtaining comparison-result data based on outputs from said multiplying means, said comparison-result data being hry=min (aq1*g, ap1*m), hrm=min (aq2*, ap2*y), hgy=min (aq3*r, ap3*c), hgc=min (aq4*b, ap4*y), hbm=min (aq5*r, ap5*c) and hbc=min (aq6*g, ap6*m), with min (A, B) indicating a minimum value of A and B; and means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data;
said arithmetic means includes means for obtaining product terms and fraction terms based on each of said hue data, and
the matrix calculator performs the matrix calculation using said comparison-result data from said comparison-result data generating means, said outputs from said arithmetic means, said hue data from said hue data calculating means and said minimum value xcex1 from said calculating means, to thereby obtain color-converted image data.
It may be so arranged that said calculating means for calculating said maximum and minimum values xcex2 and xcex1 includes means for obtaining complementary color data C, M and Y of cyan, magenta and yellow from image data R, G and B and calculating a maximum value xcex2 and a minimum value xcex1 of said complementary color data C, M and Y,
said hue data calculating means determines complementary color data C, M and Y from image data R, G and B and calculating hue data r, g, b, y, m and c by subtraction in accordance with:
r=xcex2xe2x88x92C,
g=xcex2xe2x88x92M,
b=xcex2xe2x88x92Y,
y=Yxe2x88x92xcex1,
m=Mxe2x88x92xcex1,
and
c=Cxe2x88x92xcex1
based on said complementary color data and said maximum and minimum values xcex2 and xcex1,
said comparison-result data generating means includes multiplying means for multiplying respective hue data by calculation coefficients aq1 to aq6 and ap1 to ap6; means for obtaining comparison-result data based on outputs from said multiplying means, said comparison-result data being hry=min (aq1*g, ap1*m), hrm=min (aq2*b, ap2*y), hgy=min (aq3*r, ap3*c), hgc=min (aq4*b, ap4*y), hbm=min (aq5*r, ap5*c) and hbc=min (aq6*g, ap6*m), with min (A, B) indicating a minimum value of A and B; and means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data,
said arithmetic means includes means for obtaining product terms and fraction terms based on each of said hue data, and
said matrix calculator performs the matrix calculation using said comparison-result data from said comparison-result data generating means, said outputs from said arithmetic means, said hue data from said hue data calculating means and said minimum value xcex1 from said calculating means, to thereby obtain color-converted image data.
It may be so arranged that said calculating means for calculating said maximum and minimum values xcex2 and xcex1 calculates a maximum value xcex2 and a minimum value xcex1 of the image data R, G and B,
said hue data calculating means calculates hue data r, g, b, y, m and c by subtraction in accordance with:
r=Rxe2x88x92xcex1,
g=Gxe2x88x92xcex1,
b=Bxe2x88x92xcex1,
y=xcex2xe2x88x92B,
m=xcex2xe2x88x92G,
and
xe2x80x83c=xcex2xe2x88x92R;
based on inputted image data R, G and B and said maximum and minimum values xcex2 and xcex1 outputted from said calculating means,
said comparison-result data generating means includes
multiplying means for multiplying respective hue data by calculation coefficients aq1 to aq6 and aq1 to ap6;
means for obtaining comparison-result data based on outputs from said multiplying means, said comparison-result data being hry=min (aq1*g, ap1*m), hrm=min (aq2*b, ap2*y), hgy=min (aq3*r, ap3*c), hgc=min (aq4*b, ap4*y), hbm=min (aq5*r, ap5*c) and hbc=min (aq6*g, ap6*m), with min (A, B) indicating a minimum value of A and B;
means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, and
means for obtaining comparison-result data between the hue data r, g, b and between the hue data y, m, c;
said arithmetic means includes means for obtaining product terms based on each of said hue data, and
said matrix calculator performs the matrix calculation using said comparison-result data from said comparison-result data generating means, said outputs from said arithmetic means, said hue data from said hue data calculating means and said minimum value xcex1 from said calculating means, to thereby obtain color-converted image data.
It may be so arranged that said calculating means for calculating said maximum and minimum values xcex2 and xcex1 includes means for obtaining complementary color data C, M and Y
from image data R, C and B and calculating a maximum value xcex2 and xcex1 minimum value xcex1 of said complementary color data C, M and Y,
said hue data calculating means determines complementary color data C, M and Y from image data R, G and B and calculating hue data r, g, b, y, m and c by subtraction in accordance with:
r=xcex2xe2x88x92C,
g=xcex2xe2x88x92M,
b=xcex2xe2x88x92Y,
y=Yxe2x88x92xcex1,
m=Mxe2x88x92xcex1,
and
c=Cxe2x88x92xcex1
based on said complementary color data and said maximum and minimum values xcex2 and xcex1,
said comparison-result data generating means includes multiplying
means for multiplying respective hue data by calculation coefficients aq1 to aq6 and ap1 to ap6;
means for obtaining comparison-result data based on outputs from said multiplying means, said comparison-result data being hry=min (aq1*g, ap1*m), hrm=min (aq2*b, ap2*y), hgy=min (aq3*r, ap3*c), hgc=min (aq4*b, ap4*y), hbm=min (aq5*r, ap5*c) and hbc=min (aq6*g, ap6*m), with min (A, B) indicating a minimum value of A and B;
means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data; and
means for obtaining comparison-result data between the hue data r, g and b, and between the hue data y, m and c;
said arithmetic means includes means for obtaining product terms based on each of said hue data, and
said matrix calculator performs the matrix calculation using said comparison-result data from said comparison-result data generating means, said outputs from said arithmetic means, said hue data from said hue data calculating means and said minimum value xcex1 from said calculating means, to thereby obtain color-converted image data.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said hue data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=1 to 18),
said matrix calculator performs the matrix calculation on calculation terms in the form of said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (1) below:                               [                                                    R                                                                    G                                                                    B                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    r                                                                                        g                                                                                        b                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                                                ⁢                                              c                        *                        m                                                                                                                                                                              ⁢                                              m                        *                        y                                                                                                                                                                              ⁢                                              y                        *                        c                                                                                                                                                                              ⁢                                              r                        *                        g                                                                                                                                                                              ⁢                                              g                        *                        b                                                                                                                                                                              ⁢                                              b                        *                        r                                                                                                                                                                              ⁢                                              c                        *                                                  m                          /                                                      (                                                          c                              +                              m                                                        )                                                                                                                                                                                                                                ⁢                                              m                        *                                                  y                          /                                                      (                                                          m                              +                              y                                                        )                                                                                                                                                                                                                                ⁢                                              y                        *                                                  c                          /                                                      (                                                          y                              +                              c                                                        )                                                                                                                                                                                                                                ⁢                                              r                        *                                                  g                          /                                                      (                                                          r                              +                              g                                                        )                                                                                                                                                                                                                                ⁢                                              g                        *                                                  b                          /                                                      (                                                          g                              +                              b                                                        )                                                                                                                                                                                                                                ⁢                                              b                        *                                                  r                          /                                                      (                                                          b                              +                              r                                                        )                                                                                                                                                                                                                                ⁢                                              min                        ⁡                                                  (                                                      r                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              r                              ⁢                                                              xe2x80x83                                                            ⁢                              y                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      r                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              r                              ⁢                                                              xe2x80x83                                                            ⁢                              m                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      g                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              g                              ⁢                                                              xe2x80x83                                                            ⁢                              y                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      g                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              g                              ⁢                                                              xe2x80x83                                                            ⁢                              c                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      b                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              b                              ⁢                                                              xe2x80x83                                                            ⁢                              m                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      b                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              b                              ⁢                                                              xe2x80x83                                                            ⁢                              c                                                                                )                                                                                                                                ]                                +                      [                                                            α                                                                              α                                                                              α                                                      ]                                              (        1        )            
to thereby obtain color-converted image data.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said hue data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=1 to 18),
said matrix calculator performs the matrix calculation on calculation terms in the form of said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (2) below:                               [                                                    C                                                                    M                                                                    Y                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    c                                                                                        m                                                                                        y                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                                                ⁢                                              c                        *                        m                                                                                                                                                                              ⁢                                              m                        *                        y                                                                                                                                                                              ⁢                                              y                        *                        c                                                                                                                                                                              ⁢                                              r                        *                        g                                                                                                                                                                              ⁢                                              g                        *                        b                                                                                                                                                                              ⁢                                              b                        *                        r                                                                                                                                                                              ⁢                                              c                        *                                                  m                          /                                                      (                                                          c                              +                              m                                                        )                                                                                                                                                                                                                                ⁢                                              m                        *                                                  y                          /                                                      (                                                          m                              +                              y                                                        )                                                                                                                                                                                                                                ⁢                                              y                        *                                                  c                          /                                                      (                                                          y                              +                              c                                                        )                                                                                                                                                                                                                                ⁢                                              r                        *                                                  g                          /                                                      (                                                          r                              +                              g                                                        )                                                                                                                                                                                                                                ⁢                                              g                        *                                                  b                          /                                                      (                                                          g                              +                              b                                                        )                                                                                                                                                                                                                                ⁢                                              b                        *                                                  r                          /                                                      (                                                          b                              +                              r                                                        )                                                                                                                                                                                                                                ⁢                                              min                        ⁡                                                  (                                                      r                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              r                              ⁢                                                              xe2x80x83                                                            ⁢                              y                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      r                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              r                              ⁢                                                              xe2x80x83                                                            ⁢                              m                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      g                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              g                              ⁢                                                              xe2x80x83                                                            ⁢                              y                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      g                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              g                              ⁢                                                              xe2x80x83                                                            ⁢                              c                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      b                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              b                              ⁢                                                              xe2x80x83                                                            ⁢                              m                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      b                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              b                              ⁢                                                              xe2x80x83                                                            ⁢                              c                                                                                )                                                                                                                                ]                                +                      [                                                            α                                                                              α                                                                              α                                                      ]                                              (        2        )            
to thereby obtain color-converted image data.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said hue data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=1 to 19),
said matrix calculator performs the matrix calculation on calculation terms in the form of said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (3) below:                               [                                                    R                                                                    G                                                                    B                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    r                                                                                        g                                                                                        b                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                                                ⁢                                              c                        *                        m                                                                                                                                                                              ⁢                                              m                        *                        y                                                                                                                                                                              ⁢                                              y                        *                        c                                                                                                                                                                              ⁢                                              r                        *                        g                                                                                                                                                                              ⁢                                              g                        *                        b                                                                                                                                                                              ⁢                                              b                        *                        r                                                                                                                                                                              ⁢                                              c                        *                                                  m                          /                                                      (                                                          c                              +                              m                                                        )                                                                                                                                                                                                                                ⁢                                              m                        *                                                  y                          /                                                      (                                                          m                              +                              y                                                        )                                                                                                                                                                                                                                ⁢                                              y                        *                                                  c                          /                                                      (                                                          y                              +                              c                                                        )                                                                                                                                                                                                                                ⁢                                              r                        *                                                  g                          /                                                      (                                                          r                              +                              g                                                        )                                                                                                                                                                                                                                ⁢                                              g                        *                                                  b                          /                                                      (                                                          g                              +                              b                                                        )                                                                                                                                                                                                                                ⁢                                              b                        *                                                  r                          /                                                      (                                                          b                              +                              r                                                        )                                                                                                                                                                                                                                ⁢                                              min                        ⁡                                                  (                                                      r                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              r                              ⁢                                                              xe2x80x83                                                            ⁢                              y                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      r                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              r                              ⁢                                                              xe2x80x83                                                            ⁢                              m                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      g                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              g                              ⁢                                                              xe2x80x83                                                            ⁢                              y                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      g                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              g                              ⁢                                                              xe2x80x83                                                            ⁢                              c                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      b                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              b                              ⁢                                                              xe2x80x83                                                            ⁢                              m                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      b                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              b                              ⁢                                                              xe2x80x83                                                            ⁢                              c                                                                                )                                                                                                                                                                                                      ⁢                      α                                                                                  ]                                                          (        3        )            
to thereby obtain color-converted image data.
With the above arrangement, by changing the coefficients of the product and fraction terms, and the first-order terms relating to the inter-hue areas, it is possible to adjust only the target hue or inter-hue area among the six hues or red, blue, green, yellow, cyan and magenta, and the six inter-hue areas, without influencing other hues and inter-hue areas, and by changing the coefficients relating to the minimum value xcex1 which is the achromatic data, it is possible to adjust only the achromatic component without influencing the hue components.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said hue data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=1 to 19),
said matrix calculator performs the matrix calculation on calculation terms in the form or said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (4) below:                               [                                                    C                                                                    M                                                                    Y                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    c                                                                                        m                                                                                        y                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                                                ⁢                                              c                        *                        m                                                                                                                                                                              ⁢                                              m                        *                        y                                                                                                                                                                              ⁢                                              y                        *                        c                                                                                                                                                                              ⁢                                              r                        *                        g                                                                                                                                                                              ⁢                                              g                        *                        b                                                                                                                                                                              ⁢                                              b                        *                        r                                                                                                                                                                              ⁢                                              c                        *                                                  m                          /                                                      (                                                          c                              +                              m                                                        )                                                                                                                                                                                                                                ⁢                                              m                        *                                                  y                          /                                                      (                                                          m                              +                              y                                                        )                                                                                                                                                                                                                                ⁢                                              y                        *                                                  c                          /                                                      (                                                          y                              +                              c                                                        )                                                                                                                                                                                                                                ⁢                                              r                        *                                                  g                          /                                                      (                                                          r                              +                              g                                                        )                                                                                                                                                                                                                                ⁢                                              g                        *                                                  b                          /                                                      (                                                          g                              +                              b                                                        )                                                                                                                                                                                                                                ⁢                                              b                        *                                                  r                          /                                                      (                                                          b                              +                              r                                                        )                                                                                                                                                                                                                                ⁢                                              min                        ⁡                                                  (                                                      r                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              r                              ⁢                                                              xe2x80x83                                                            ⁢                              y                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      r                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              r                              ⁢                                                              xe2x80x83                                                            ⁢                              m                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      g                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              g                              ⁢                                                              xe2x80x83                                                            ⁢                              y                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      g                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              g                              ⁢                                                              xe2x80x83                                                            ⁢                              c                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      b                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              b                              ⁢                                                              xe2x80x83                                                            ⁢                              m                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      b                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              b                              ⁢                                                              xe2x80x83                                                            ⁢                              c                                                                                )                                                                                                                                                                                                      ⁢                      α                                                                                  ]                                                          (        4        )            
to thereby obtain color-converted image data.
With the above arrangement, by changing the coefficients or the product and fraction terms, and the first-order terms relating to the inter-hue areas, it is possible to adjust only the target hue or inter-hue area among the six hues of red, blue, green, yellow, cyan and magenta, and the six inter-hue areas, without influencing other hues and inter-hue areas, and by changing the coefficients relating to the minimum value xcex1 which is the achromatic data, it is possible to adjust only the achromatic component without influencing the hue components.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said hue data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=1 to 18),
said matrix calculator performs the matrix calculation on calculation terms in the form of said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (5) below:                               [                                                    R                                                                    G                                                                    B                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    r                                                                                        g                                                                                        b                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                                                ⁢                                              c                        *                        m                                                                                                                                                                              ⁢                                              m                        *                        y                                                                                                                                                                              ⁢                                              y                        *                        c                                                                                                                                                                              ⁢                                              r                        *                        g                                                                                                                                                                              ⁢                                              g                        *                        b                                                                                                                                                                              ⁢                                              b                        *                        r                                                                                                                                                                              ⁢                                              c                        *                                                  m                          /                                                      (                                                          c                              +                              m                                                        )                                                                                                                                                                                                                                ⁢                                              m                        *                                                  y                          /                                                      (                                                          m                              +                              y                                                        )                                                                                                                                                                                                                                ⁢                                              y                        *                                                  c                          /                                                      (                                                          y                              +                              c                                                        )                                                                                                                                                                                                                                ⁢                                              r                        *                                                  g                          /                                                      (                                                          r                              +                              g                                                        )                                                                                                                                                                                                                                ⁢                                              g                        *                                                  b                          /                                                      (                                                          g                              +                              b                                                        )                                                                                                                                                                                                                                ⁢                                              b                        *                                                  r                          /                                                      (                                                          b                              +                              r                                                        )                                                                                                                                                                                                                                ⁢                                              min                        ⁡                                                  (                                                      y                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              r                              ⁢                                                              xe2x80x83                                                            ⁢                              y                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      y                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              g                              ⁢                                                              xe2x80x83                                                            ⁢                              y                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      c                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              g                              ⁢                                                              xe2x80x83                                                            ⁢                              c                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      c                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              b                              ⁢                                                              xe2x80x83                                                            ⁢                              c                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      m                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              b                              ⁢                                                              xe2x80x83                                                            ⁢                              m                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      m                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              r                              ⁢                                                              xe2x80x83                                                            ⁢                              m                                                                                )                                                                                                                                ]                                +                      [                                                            α                                                                              α                                                                              α                                                      ]                                              (        5        )            
to thereby obtain color-converted image data.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said hue data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=1 to 18),
said matrix calculator performs the matrix calculation on calculation terms in the form of said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (6) below:                               [                                                    C                                                                    M                                                                    Y                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    c                                                                                        m                                                                                        y                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                                                ⁢                                              c                        *                        m                                                                                                                                                                              ⁢                                              m                        *                        y                                                                                                                                                                              ⁢                                              y                        *                        c                                                                                                                                                                              ⁢                                              r                        *                        g                                                                                                                                                                              ⁢                                              g                        *                        b                                                                                                                                                                              ⁢                                              b                        *                        r                                                                                                                                                                              ⁢                                              c                        *                                                  m                          /                                                      (                                                          c                              +                              m                                                        )                                                                                                                                                                                                                                ⁢                                              m                        *                                                  y                          /                                                      (                                                          m                              +                              y                                                        )                                                                                                                                                                                                                                ⁢                                              y                        *                                                  c                          /                                                      (                                                          y                              +                              c                                                        )                                                                                                                                                                                                                                ⁢                                              r                        *                                                  g                          /                                                      (                                                          r                              +                              g                                                        )                                                                                                                                                                                                                                ⁢                                              g                        *                                                  b                          /                                                      (                                                          g                              +                              b                                                        )                                                                                                                                                                                                                                ⁢                                              b                        *                                                  r                          /                                                      (                                                          b                              +                              r                                                        )                                                                                                                                                                                                                                ⁢                                              min                        ⁡                                                  (                                                      y                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              r                              ⁢                                                              xe2x80x83                                                            ⁢                              y                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      y                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              g                              ⁢                                                              xe2x80x83                                                            ⁢                              y                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      c                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              g                              ⁢                                                              xe2x80x83                                                            ⁢                              c                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      c                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              b                              ⁢                                                              xe2x80x83                                                            ⁢                              c                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      m                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              b                              ⁢                                                              xe2x80x83                                                            ⁢                              m                                                                                )                                                                                                                                                                                                      ⁢                                              min                        ⁡                                                  (                                                      m                            ,                                                          h                              ⁢                                                              xe2x80x83                                                            ⁢                              r                              ⁢                                                              xe2x80x83                                                            ⁢                              m                                                                                )                                                                                                                                ]                                +                      [                                                            α                                                                              α                                                                              α                                                      ]                                              (        6        )            
to thereby obtain color-converted image data.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said hue data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=to 19),
said matrix calculator performs the matrix calculation on calculation terms in the form of said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (7) below:                               [                                                    R                                                                    G                                                                    B                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    r                                                                                        g                                                                                        b                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                          c                      *                      m                                                                                                                                  m                      *                      y                                                                                                                                  y                      *                      c                                                                                                                                  r                      *                      g                                                                                                                                  g                      *                      b                                                                                                                                  b                      *                      r                                                                                                                                  c                      *                                              m                        /                                                  (                                                      c                            +                            m                                                    )                                                                                                                                                                                m                      *                                              y                        /                                                  (                                                      m                            +                            y                                                    )                                                                                                                                                                                y                      *                                              c                        /                                                  (                                                      y                            +                            c                                                    )                                                                                                                                                                                r                      *                                              g                        /                                                  (                                                      r                            +                            g                                                    )                                                                                                                                                                                g                      *                                              b                        /                                                  (                                                      g                            +                            b                                                    )                                                                                                                                                                                b                      *                                              r                        /                                                  (                                                      b                            +                            r                                                    )                                                                                                                                                                                min                      ⁡                                              (                                                  y                          ,                          hry                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          hgy                                                )                                                                                                                                                        min                      ⁡                                              (                                                  c                          ,                          hgc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  c                          ,                          hbc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          hbm                                                )                                                                                                                                                        min                      (                                              m                        ,                        hrm                                            ⁢                                              xe2x80x83                                            )                                                                                                            α                                                              ]                                                          (        7        )            
to thereby obtain color-converted image data.
With the above arrangement, by changing the coefficients of the product and fraction terms, and the first-order terms relating to the inter-hue areas, it is possible to adjust only the target hue or inter-hue area among the six hues of red, blue, green, yellow, cyan and magenta, and the six inter-hue areas, without influencing other hues and inter-hue areas, and by changing the coefficients relating to the minimum value xcex1 which is the achromatic data, it is possible to adjust only the achromatic component without influencing the hue components.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said hue data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=1 to 19),
said matrix calculator performs the matrix calculation on calculation terms in the form of said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (8) below:                               [                                                    C                                                                    M                                                                    Y                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    c                                                                                        m                                                                                        y                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                          c                      *                      m                                                                                                                                  m                      *                      y                                                                                                                                  y                      *                      c                                                                                                                                  r                      *                      g                                                                                                                                  g                      *                      b                                                                                                                                  b                      *                      r                                                                                                                                  c                      *                                              m                        /                                                  (                                                      c                            +                            m                                                    )                                                                                                                                                                                m                      *                                              y                        /                                                  (                                                      m                            +                            y                                                    )                                                                                                                                                                                y                      *                                              c                        /                                                  (                                                      y                            +                            c                                                    )                                                                                                                                                                                r                      *                                              g                        /                                                  (                                                      r                            +                            g                                                    )                                                                                                                                                                                g                      *                                              b                        /                                                  (                                                      g                            +                            b                                                    )                                                                                                                                                                                b                      *                                              r                        /                                                  (                                                      b                            +                            r                                                    )                                                                                                                                                                                min                      ⁡                                              (                                                  y                          ,                          hry                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          hgy                                                )                                                                                                                                                        min                      ⁡                                              (                                                  c                          ,                          hgc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  c                          ,                          hbc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          hbm                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          hrm                                                )                                                                                                                                  α                                                              ]                                                          (        8        )            
to thereby obtain color-converted image data.
With the above arrangement, by changing the coefficients of the product and fraction terms, and the first-order terms relating to the inter-hue areas, it is possible to adjust only the target hue or inter-hue area among the six hues of red, blue, green, yellow, cyan and magenta, and the six inter-hue areas, without influencing other hues and inter-hue area, and by changing the coefficients relating to the minimum value xcex1 which is the achromatic data, it is possible to adjust only the achromatic component without influencing the hue components.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said hue data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=1 to 18),
said matrix calculator performs the matrix calculation on calculation terms in the form of said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (9) below:                               [                                                    R                                                                    G                                                                    B                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    r                                                                                        g                                                                                        b                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                          c                      *                      m                                                                                                                                  m                      *                      y                                                                                                                                  y                      *                      c                                                                                                                                  r                      *                      g                                                                                                                                  g                      *                      b                                                                                                                                  b                      *                      r                                                                                                                                  min                      ⁡                                              (                                                  c                          ,                          m                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          y                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          c                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          g                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          b                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          r                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          hry                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          hrm                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          hgy                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          hgc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          hbm                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          hbc                                                )                                                                                                        ]                                +                      [                                                            α                                                                              α                                                                              α                                                      ]                                              (        9        )            
to thereby obtain color-converted image data.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said hue data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=1 to 18),
said matrix calculator performs the matrix calculation on calculation terms in the form of said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (10) below:                               [                                                    C                                                                    M                                                                    Y                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    c                                                                                        m                                                                                        y                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                          c                      *                      m                                                                                                                                  m                      *                      y                                                                                                                                  y                      *                      c                                                                                                                                  r                      *                      g                                                                                                                                  g                      *                      b                                                                                                                                  b                      *                      r                                                                                                                                  min                      ⁡                                              (                                                  c                          ,                          m                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          y                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          c                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          g                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          b                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          r                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          hry                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          hrm                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          hgy                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          hgc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          hbm                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          hbc                                                )                                                                                                        ]                                +                      [                                                            α                                                                              α                                                                              α                                                      ]                                              (        10        )            
to thereby obtain color-converted image data.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said hue data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=1 to 19),
said matrix calculator performs the matrix calculation on calculation terms in the form of said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (11) below:                               [                                                    R                                                                    G                                                                    B                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    r                                                                                        g                                                                                        b                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                          c                      *                      m                                                                                                                                  m                      *                      y                                                                                                                                  y                      *                      c                                                                                                                                  r                      *                      g                                                                                                                                  g                      *                      b                                                                                                                                  b                      *                      r                                                                                                                                  min                      ⁡                                              (                                                  c                          ,                          m                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          y                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          c                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          g                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          b                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          r                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          hry                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          hrm                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          hgy                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          hgc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          hbm                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          hbc                                                )                                                                                                                                  α                                                              ]                                                          (        11        )            
to thereby obtain color-converted image data.
With the above arrangement, by changing the coefficients of the product terms, the first-order terms in the form of comparison-result data based on the hue data, relating to specific hues, and the first-order terms relating to the inter-hue areas, it is possible to adjust only the target hue or inter-hue area among the six hues of red, blue, green, yellow, cyan and magenta, and the six inter-hue areas, without influencing other hues and inter-hue areas, and by changing the coefficients relating to the minimum value xcex1 which is the achromatic data, it is possible to adjust only the achromatic component without influencing the hue components.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said hue data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=1 to 19),
said matrix calculator performs the matrix calculation on calculation terms in the form of said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (10) below:                               [                                                    C                                                                    M                                                                    Y                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    c                                                                                        m                                                                                        y                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                          c                      *                      m                                                                                                                                  m                      *                      y                                                                                                                                  y                      *                      c                                                                                                                                  r                      *                      g                                                                                                                                  g                      *                      b                                                                                                                                  b                      *                      r                                                                                                                                  min                      ⁡                                              (                                                  c                          ,                          m                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          y                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          c                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          g                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          b                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          r                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          hry                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          hrm                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          hgy                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          hgc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          hbm                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          hbc                                                )                                                                                                                                  α                                                              ]                                                          (        12        )            
to thereby obtain color-converted image data.
With the above arrangement, by changing the coefficients of the product terms, the first-order terms in the form of comparison-result data based on the hue data, relating to specific hues, and the first-order terms relating to the inter-hue areas, it is possible to adjust only the target hue or inter-hue area among the six hues of red, blue, green, yellow, cyan and magenta, and the six inter-hue areas, without influencing other hues and inter-hue areas, and by changing the coefficients relating to the minimum value xcex1 which is the achromatic data, it is possible to adjust only the achromatic component without influencing the hue components.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said hue data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=1 to 18),
said matrix calculator performs the matrix calculation on calculation terms in the form of said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (13) below:                               [                                                    R                                                                    G                                                                    B                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    r                                                                                        g                                                                                        b                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                          c                      *                      m                                                                                                                                  m                      *                      y                                                                                                                                  y                      *                      c                                                                                                                                  r                      *                      g                                                                                                                                  g                      *                      b                                                                                                                                  b                      *                      r                                                                                                                                  min                      ⁡                                              (                                                  c                          ,                          m                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          y                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          c                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          g                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          b                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          r                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          hry                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          hgy                                                )                                                                                                                                                        min                      ⁡                                              (                                                  c                          ,                          hgc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  c                          ,                          hbc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          hbm                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          hrm                                                )                                                                                                        ]                                +                      [                                                            α                                                                              α                                                                              α                                                      ]                                              (        13        )            
to thereby obtain color-converted image data.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said hue data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=1 to 18),
said matrix calculator performs the matrix calculation on calculation terms in the form of said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (14) below:                               [                                                    C                                                                    M                                                                    Y                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    c                                                                                        m                                                                                        y                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                          c                      *                      m                                                                                                                                  m                      *                      y                                                                                                                                  y                      *                      c                                                                                                                                  r                      *                      g                                                                                                                                  g                      *                      b                                                                                                                                  b                      *                      r                                                                                                                                  min                      ⁡                                              (                                                  c                          ,                          m                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          y                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          c                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          g                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          b                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          r                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          hry                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          hgy                                                )                                                                                                                                                        min                      ⁡                                              (                                                  c                          ,                          hgc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  c                          ,                          hbc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          hbm                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          hrm                                                )                                                                                                        ]                                +                      [                                                            α                                                                              α                                                                              α                                                      ]                                              (        14        )            
to thereby obtain color-converted image data.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said hue data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=1 to 19),
said matrix calculator performs the matrix calculation on calculation terms in the form of said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (15) below:                               [                                                    R                                                                    G                                                                    B                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    r                                                                                        g                                                                                        b                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                          c                      *                      m                                                                                                                                  m                      *                      y                                                                                                                                  y                      *                      c                                                                                                                                  r                      *                      g                                                                                                                                  g                      *                      b                                                                                                                                  b                      *                      r                                                                                                                                  min                      ⁡                                              (                                                  c                          ,                          m                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          y                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          c                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          g                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          b                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          r                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          hry                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          hgy                                                )                                                                                                                                                        min                      ⁡                                              (                                                  c                          ,                          hgc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  c                          ,                          hbc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          hbm                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          hrm                                                )                                                                                                                                  α                                                              ]                                                          (        15        )            
to thereby obtain color-converted image data.
With the above arrangement, by changing the coefficients of the product terms, the first-order terms in the form of comparison-result data based on the hue data, relating to specific hues, and the first-order terms relating to the inter-hue areas, it is possible to adjust only the target hue or inter-hue area among the six hues of red, blue, green, yellow, cyan arid magenta, and the six inter-hue areas, without influencing other hues and inter-hue areas, and by changing the coefficients relating to the minimum value xcex1 which is the achromatic data, it is possible to adjust only the achromatic component without influencing the hue components.
It may be so arranged that said means for obtaining comparison-result data based on comparison between each of said comparison-result data and each of said hue data, in said comparison-result data generating means, determines comparison-result data based on comparison between said comparison-result data hry, hrm, hgy, hgc, hbm and hbc, and said time data r, g and b,
said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) and Fij (i=1 to 3, j=1 to 19),
said matrix calculator performs the matrix calculation on calculation terms in the form of said comparison-result data and said hue data and said minimum value xcex1 outputted from said calculating means by a matrix calculation formula (16) below:                               [                                                    C                                                                    M                                                                    Y                                              ]                =                                            (              Eij              )                        ⁡                          [                                                                    c                                                                                        m                                                                                        y                                                              ]                                +                                    (              Fij              )                        ⁡                          [                                                                                          c                      *                      m                                                                                                                                  m                      *                      y                                                                                                                                  y                      *                      c                                                                                                                                  r                      *                      g                                                                                                                                  g                      *                      b                                                                                                                                  b                      *                      r                                                                                                                                  min                      ⁡                                              (                                                  c                          ,                          m                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          y                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          c                                                )                                                                                                                                                        min                      ⁡                                              (                                                  r                          ,                          g                                                )                                                                                                                                                        min                      ⁡                                              (                                                  g                          ,                          b                                                )                                                                                                                                                        min                      ⁡                                              (                                                  b                          ,                          r                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          hry                                                )                                                                                                                                                        min                      ⁡                                              (                                                  y                          ,                          hgy                                                )                                                                                                                                                        min                      ⁡                                              (                                                  c                          ,                          hgc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  c                          ,                          hbc                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          hbm                                                )                                                                                                                                                        min                      ⁡                                              (                                                  m                          ,                          hrm                                                )                                                                                                                                  α                                                              ]                                                          (        16        )            
to thereby obtain color-converted image data.
With the above arrangement, by changing the coefficients of the product terms, the first-order terms in the form of comparison-result data based on the hue data, relating to specific hues, and the first-order terms relating to the inter-hue areas, it is possible to adjust only the target hue or inter-hue area among the six hues of red, blue, green, yellow, cyan and magenta, and the six inter-hue areas, without influencing other hues and inter-hue areas, and by changing the coefficients relating to the minimum value xcex1 which is the achromatic data, it is possible to adjust only the achromatic component without influencing the hue components.
It may be so arranged that said coefficient generating means generates specified matrix coefficients Eij (i=1 to 3, j=1 to 3) based on a formula (17) below:                               (          Eij          )                =                  [                                                    1                                            0                                            0                                                                    0                                            1                                            0                                                                    0                                            0                                            1                                              ]                                    (        17        )            
and the matrix coefficients Fij (i=1 to 3, j=1 to 18, or j=1 to 19)
are generated such that, of the coefficients Fij, the coefficients for said product term based on each hue data outputted from said calculating means are set to zero, and other coefficients are set to specified values.
It may be so arranged that said multiplying means for multiplying said hue data by specified calculation coefficients aq1 to aq6 and aq1 to ap6, in said comparison-result data generating means, performs calculation on said hue data and said calculation coefficients by setting said calculation coefficients aq1 to aq6 and ap1 to ap6 to integral values of 2n, with n being an integer, and by bit shifting.
It may be so arranged that said calculating means for calculating a maximum value xcex2 and a maximum value xcex1 of said image data calculates a maximum value xcex2 and a minimum value xcex1 using said image data, and generating an identification code indicating the hue data which is of a value zero according to the image data or the complementary color data which are the largest and the smallest, and
based on the identification code outputted from said calculation means, comparison-result data is generated by said comparison-result data generating means, and matrix coefficients are generated by said coefficient generating means, and matrix calculation is performed based on the coefficients from said coefficient generating means according to said identification code from said calculating means, to thereby obtain color-converted image data, or complementary color data.
According to another aspect of the invention, there is provided a color conversion method for performing pixel-by-pixel conversion of image data R, G and B of three colors, red, green and blue, comprising the steps of:
calculating a maximum value xcex2 and a minimum value xcex1 for each pixel of said image data;
calculating hue data r, g, b, y, m and c based on said image data and said maximum and minimum values xcex2 and xcex1, and generating comparison-result data based on each of said calculated hue data;
performing calculation using each or said calculated hue data; and
performing matrix calculation using said comparison-result data, said calculation output, said hue data and said minimum value xcex1 and based on specified matrix coefficients, to thereby obtain color-converted image data.
With the above arrangement, it is possible to independently correct, in addition to the six hues of red, blue, green, yellow, cyan and magenta, the six inter-hue areas of red-yellow, yellow-green, green-cyan, cyan-blue, blue-magenta, and magenta-red.
It is also possible to flexibly change the conversion characteristics, and the large-capacity memory is not required.
It may be so arranged that the method comprises the steps of:
calculating a maximum value xcex2 and a minimum value for said image data R, G and B;
calculating hue data r, g, b, y, m and c based on subtraction in accordance with:
r=Rxe2x88x92xcex1,
g=Gxe2x88x92xcex1,
b=Bxe2x88x92xcex1,
y=xcex2xe2x88x92B,
m=xcex2xe2x88x92G,
and
c=xcex2xe2x88x92R
on said inputted image data R, G and B and said maximum and minimum values xcex2 and xcex1;
multiplying said hue data by specified calculation coefficients aq1 to aq6 and aq1 to ap6, obtaining comparison-result data hry=min (aq1*g, ap1*m), hrm=min (aq2*b, ap2*y), hgy=min (aq3*r, ap3*c), hgc=min (aq4*b, ap4*y), hbm=min (aq5*r, ap5*c) and hbc=min (aq6*g, ap6*m) (where min (A, B) indicates the minimum value of A and B) using multiplied output and obtaining comparison-result data between said comparison-result data and said hue data;
obtaining product terms and fraction terms based on each of said hue data; and
performing matrix calculation using said comparison-result data, the calculation output, said hue data and said minimum value xcex1, to thereby obtain color-converted image data.
It may be so arranged that the method comprises the steps of:
calculating a maximum value xcex2 and a minimum value xcex1 of complementary color data C, M and Y of cyan, magenta and yellow from said image data R, C and B;
calculating hue data r, g, b, y, m and c based on subtraction in accordance with:
xe2x80x83r=xcex2xe2x88x92C,
g=xcex2xe2x88x92M,
b=xcex2xe2x88x92Y,
y=Yxe2x88x92xcex1,
m=Mxe2x88x92xcex1,
and
c=Cxe2x88x92xcex1
on said complementary color data C, M and Y and said maximum and minimum values xcex2 and xcex1;
using outputted results of multiplying said hue data by specified calculation coefficients aq1 to aq6 and aq1 to ap6, to obtain comparison-result data hry=min (aq1*g, ap1*m), hrm=min (aq2*b, ap2*y), hgy=min (aq3*r, ap3*c), hgc=min (aq4*b, ap4*y), hbm=min (aq5*r, ap5*c) and hbc=min (aq6*g, ap6*m) (where min (A, B) indicates the minimum value of A and B), and obtaining comparison-result data between said comparison-result data and said hue data;
obtaining product terms and fraction terms for each line data; and
performing matrix calculation using said comparison-result data, said calculation outputs, said hue data and said minimum value xcex1, to thereby obtain color-converted complementary color data.
It may be so arranged that the method comprises the steps of:
calculating a maximum value xcex2 and a minimum value for said image data R, C and B;
calculating hue data r, g, b, y, in and c based on subtraction in accordance with:
r=Rxe2x88x92xcex1,
g=Cxe2x88x92xcex1,
b=Bxe2x88x92xcex1,
xe2x80x83y=xcex2xe2x88x92B,
m=xcex2xe2x88x92G,
and
c=xcex2xe2x88x92R
on said
image data R, G and B and said maximum and minimum values xcex2 and xcex1;
multiplying said hue data by specified calculation coefficients aq1 to aq6 and ap1 to ap6, obtaining comparison-result data hry=min (aq1*g, ap1*m), hrm=min (aq2*b, ap2*y), hgy=min (aq3*r, ap3*c), hgc=min (aq4*b, ap4*y), hbm=min (aq5*r, ap5*c) and hbc=min (aq6*g, ap6*m) (where min (A, B) indicates the minimum value of A and B) using multiplied output,
obtaining comparison-result data between said comparison-result data and said hue data;
obtaining comparison-result data between the hue data r, g, b and between the hue data y, m, c;
obtaining product terms based on each or said hue data; and
performing matrix calculation using said comparison-result data, the calculation output, said hue data and said minimum value xcex1, to thereby obtain color-converted image data.
It may be so arranged that the method comprises the steps of:
obtaining complementary color data C, M and Y from said image data R, G and B, and calculating a maximum value xcex2 and a minimum value xcex1 of said complementary color data;
obtaining complementary color data from said image data R, G and B;
calculating hue data r, g, b, y, m and c based on subtraction in accordance with:
xe2x80x83r=xcex2xe2x88x92C,
g=xcex2xe2x88x92M,
b=xcex2xe2x88x92Y,
y=Yxe2x88x92xcex1,
m=Mxe2x88x92xcex1,
and
c=Cxe2x88x92xcex1
on said complementary color data and said maximum and minimum values xcex2 and xcex1;
multiplying said hue data by specified calculation coefficients aq1 to aq6 and ap1 to ap6;
using outputs of said multiplication to obtain comparison-result data hry=min (aq1*g, ap1*m), hrm=min (aq2*b, ap2*y), hgy=min (aq3*r, ap3*c), hgc=min (aq4*b, ap4*y), hbm=min (aq5*r, ap5*c) and hbc=min (aq6*g, ap6*m) (where min (A, B) indicates the minimum value of A and B);
obtaining comparison-result data based on comparison between each said comparison-result data and said hue data;
obtaining comparison-result data based on comparison among said hue data r, g and b and among said hue data y, m and c;
obtaining a product term for each of said hue data; and
performing matrix calculation by using said comparison-result data, said calculated outputs, said hue data and said minimum value xcex1, and thereby obtaining color-converted complementary color data.